Boletín de aludes

Northwest Mountains

Crested Butte Avalanche Center
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Peligro de aludes

Thu
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Bigger storm totals in the Northwest Mountains mean that instabilities in the new snow will be larger and more common.  Avalanche conditions will be more dangerous as you gain elevation into wind-loaded terrain.  Manage for instabilities in the new snow; expect slabs to be thicker and potentially more sensitive on leeward slopes.  On high, northerly aspects, there's a rare chance you can trigger a much larger slab in steep terrain where snow depths are thin and variable.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    The new and windblown snow has formed fresh slabs, especially on terrain features favored by westerly winds.  These slabs formed over various surfaces; some could remain sensitive to triggers today.   Carefully assess slab size and terrain consequences before riding in steep terrain.  Cracking or collapsing indicates unstable snow.  The problem is smaller and less common at lower elevations.     

    A small natural wind slab that ran on Monday in the Anthracites.  Expect slabs to be thicker today after some areas received another foot of snow last night.  Photo: Miles Morris

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    2–2.5

    The snowpack remains winter-like on high, northerly aspects, and faceted weak layers linger near the bottom of the snowpack.   Persistent and deep persistent slabs are most likely triggered by cornice falls, or there's a slight chance you can trigger one from a shallow or rocky part of a steep slope.   Terrain where the snowpack is unusually shallow from wind effects or previous avalanche activity is most concerning.  You can reduce your risk by traveling where the snowpack is deep and uniform, and you can avoid the problem on sunnier aspects that have a spring-like snowpack that saw extensive meltwater last week.  

    A large persistent slab on Gothic triggered by a shallower wet avalanche on 3/25.

Avalanche Discussion

Storm totals range from 20" (~1.5" SWE) at Irwin to less than 6" in the Southeast Mountains.  Today's danger ratings highlight where instabilities in the new snow will be larger and more common.  On most terrain, you will just have to manage the new snow over firm crusts that formed during last week's meltdown.  In some cases, thin facet layers formed above these crusts and new slabs could remain sensitive today, while other slopes are likely bonding well already.   This layer is probably the source of reports of "super touchy wind slabs" and a remote triggered wind slab over the past two days near Marble.   The facet layer likely formed from melt-layer recrystallization before the storm, and we have limited data on its distribution right now.  Gather feedback on how the storm snow is behaving and use extra caution on drifted features where slabs will be thicker and stiffer.  

The only slopes that didn't see extensive meltwater into the snowpack last week are high, northerlies. A more winter-like snowpack structure exists and requires consideration for the early-season weak layers that have plagued us this winter, especially on terrain with unusually shallow snow depths. The most recent examples of the problem include a snowmobile-triggered slide on Axtell and a skier-triggered slide on Gothic. 

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